The engineering questions you get asked, and the bugs you actually hit. Drawn, one mechanism at a time, in the order the videos ship.
Why naive modulo hashing causes catastrophic cache stampedes when resizing clusters, and how the 360-degree hash ring bounds key remapping to K/N.
You cannot choose CA in distributed systems because network partitions are unavoidable. The real architectural tradeoff is between CP and AP during a network split.
When a table grows past 500 million rows, partitioning keeps query plans fast on one server while sharding scales writes across a cluster at the cost of ACID.
How reverse proxies distribute millions of requests across clusters, and why picking the wrong algorithm creates hot spots and crashes servers.
A Docker container is not a lightweight virtual machine. It is a standard Linux process wearing two kernel hats: namespaces for isolation and cgroups for resource limits.
Microservices do not eliminate complexity; they move in-memory function calls over the network into distributed systems. What you gain, what you lose, and when to switch.
RabbitMQ and SQS are message queues where messages are consumed and deleted. Kafka is an append-only distributed commit log where events are retained and replayed.
When a downstream service slows down, it can exhaust thread pools and take down your entire architecture. How the Circuit Breaker pattern isolates failure.
Rate limiters protect servers from traffic surges, DoS attacks, and abusive scraping. How token bucket and leaky bucket work, and which one your API needs.
401 means 'I don't know who you are (authenticate yourself)'. 403 means 'I know who you are, and you don't have permission'. The naming mistake in HTTP and how to use them.
XSS executes malicious code inside your user's browser. CSRF tricks your user's browser into making requests they never wanted. The key difference in one line.
String concatenation turns user input into executable database commands. Why escaping strings fails and parameterized queries always win.
